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The Chinese Remainder Theorem
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The Chinese Remainder Theorem

14 to 18

In this article we shall consider how to solve problems such as "Find all integers that leave a remainder of 1 when divided by 2, 3, and 5."

The yellow NRICH logo above the words 'Early Years', on a pink background.
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Subitising

3 to 7

In this article for EY practitioners, Dr Sue Gifford outlines what we mean by subitising and how we can teach it.

Part 1: Build your first model
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Part 1: Build Your First Model

11 to 14

With just some simple arithmetic, Julia introduces us to a basic mathematical model of the spread of infectious diseases, and then introduces us to R, one of the most important numbers in disease modelling.

Summing Consecutive Numbers
problem
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Summing Consecutive Numbers

11 to 14

15 = 7 + 8 and 10 = 1 + 2 + 3 + 4. Can you say which numbers can be expressed as the sum of two or more consecutive integers?

problem
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Marbles in a Box

11 to 16

How many winning lines can you make in a three-dimensional version of noughts and crosses?

Two and Two
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Two and Two

7 to 16

How many solutions can you find to this sum? Each of the different letters stands for a different number.

A rolled up old-fashioned treasure map.
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Treasure Hunt

7 to 14

Can you find a reliable strategy for choosing coordinates that will locate the treasure in the minimum number of guesses?

Heavy hydrocarbons
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Heavy Hydrocarbons

14 to 18
Explore the distribution of molecular masses for various hydrocarbons
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